1. Field of the Invention
The present invention relates generally to high-frequency semiconductor devices and more particularly relates to an improved biasing technique for a field effect transistor (FET).
2. Description of the Related Art
Monolithic Microwave Integrated Circuits (MMICs) typically utilize GaAs metal semiconductor field-effect transistors (MESFETs) as active devices. The control grid (gate) of a MESFET is biased negatively with respect to the source electrode so that a retarding potential barrier is presented to electrons flowing from the source to the drain.
FIG. 1 depicts the standard two power supply technique for biasing a MESFET 10 having source, gate, and drain terminals 12, 14, and 16, respectively. In FIG. 1, a first power supply 20 biases the drain 16 positively with respect to the source 12. A second power supply 22 biases the gate 16 negatively with respect to the source 12.
However, for many applications the need to provide the negative power supply increases the expense, complexity, and size of the device.
Negative gate bias has also been provided utilizing a charge pump by converting voltage from a positive power supply, but again the provision of a charge pump increases the complexity of the circuit.